Rigneault Project Abstract DEEPHIPPO DEEPHIPPO: Ultra?thin lensless endoscope for the visualization of deep hippocampus neuronal functional activity. Principal investigator: Herv Rigneault Host Institution: Aix?Marseille University, Marseille, France Project duration : 24 months Project Abstract DEEPHIPPO breaks the experimental limitations of in vivo two?photon calcium imaging in the deep brain where multiphoton (2photon and 3photon) microscopy is impossible. Using innovative multicore optical fibers together with wavefront shaping DEEPHIPPO aims at developing a novel and disruptive 2photon endoscope technology featuring a distal diameter as small as the fiber diameter. The technology will be validated to record neural activity either in CA1 or CA3 in freely moving mice. Addressing this timely biological question provides the drive for a tool development that will obviously pave the way to image deep brain structures in behaving animal models. 1